President Donald Trump, accompanied by Turkish President Recep Tayyip Erdogan, speak in the Roosevelt Room of the White House in Washington Tuesday, May 16, 2017. Evan Vucci/AP Conspiracy theories are all the rage these days.

Barely a day goes by without someone accusing someone else of engaging in fake news, post-truths, witch hunts and organized political skulduggery.

But they have been with us for a long time, influencing public opinion and major historic events. The Nazi regime continuously resorted to anti-Semitic conspiracy theories in its vile mission.

More recently, President Bashar al-Assad suppressed protests in Daraa, which he saw as a conspiracy, triggering the Syrian Civil War.

Everyday use of the term "conspiracy theory" is a pejorative one. It generally describes what we consider to be a false belief held by strange people. So how do they have any influence on public opinion or political events?

To try and find out, I examined the impact of official conspiracy theories on the Gezi Park protests in Turkey. This wave of demonstrations and violent rebuttals in May and June 2013 began as a small resistance to the attempt to demolish the Gezi Park in Taksim, one of the few green areas in central Istanbul.

On May 28, around 50 protesters camped in the park as part of a group effort to prevent its demolition. Police raided the camp twice and burned the protestors' tents. This aggression in turn provoked a dramatic spread of the protests, which brought together a wide range of political and civil groups and many more people.

Demonstrators shout nationalist slogans during a protest in front of the headquarters of the Hurriyet daily newspaper in Istanbul, Turkey, September 8, 2015. Selcuk Samiloglu/Hurriyet Daily/Reuters

The reaction of the Turkish government was a concerted attempt to discredit the social movement as a foreign conspiracy. The then prime minister (now president) Recep Tayyip Erdoğan claimed the protest was the result of a conspiracy by foreign financial groups attempting to hinder Turkish economic progress.

To understand the effect of this argument on public opinion, I analyzed online conversations about the interest rate lobby on the most popular discussion website in Turkey, Ekşi Sözlük, and their interpretations of the conspiracy account.

Most of the contributors who agreed with the official conspiracy theory idea simply expressed their belief that the government was correct in identifying a foreign plot.

Those who rejected the government's argument either argued that the government was wrong, or was inventing the conspiracy for political ends. One commented that it was "a good example of inventing an imaginary enemy."

But then looking at the online commentators' previous postings, I discovered that political stance provided a solid prediction of how they would respond to the official suggestion of a conspiracy. In other words, if the online users were pro-government before the protests, they tended to believe in the official conspiracy account. If they were critical of the government, they tended to reject the conspiracy rhetoric.

Fueling the fire

Conspiracy theories are not just harmless irrational beliefs. They have serious impact, and can be used entirely rationally to justify political views.

And because people are likely to interpret conspiracy theories in line with their political values and interests, this can increase political fragmentation.

As conspiracy theories blame certain groups for wrongdoing, they can embolden existing political divisions between groups.

In the Turkish case, this was clear. The official conspiratorial frames concerning the Gezi Park protests have contributed to national political fragmentation by adding to disagreements between government supporters and opponents.

This fragmentation is plainly visible in the Turkish government's current attempt to clamp down on anyone they choose to blame for conspiring in the failed coup attempt of July 2016. Judges, teachers and journalists have all been arrested for alleged sympathy with the coup.

Whether it's in Hitler's Germany, Assad's Syria, or contemporary Turkey, the official use of conspiracy rhetoric is a powerful political tool. It increases tensions and deepens division. Conspiracy theories are not just for crackpots and people with vivid imaginations - they are far more serious than that.

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